The purpose of the proposed research is to provide further understanding of mechanisms of immunity by more intensively studying patients with immunologic deficiency and utilizing newer modalities of therapy in T cell deficiency. Newer forms of deficiency will be sought out by testing patients with cutaneous, bone, hematological disorders as well as malformation syndromes since these groups are at high risk. In addition to classic tests of T and B cell function, membrane analysis and in vitro stimulation of B cells will be performed. T cell function will also be assessed by rosette formation and thymosin levels. Different methods to enhance repair of isolated T cell deficiency will be utilized, considering route of administration, mass of gland transplanted and synergistic or potentiating effects of spleen and/or liver.